1. Field of the Invention
The present invention relates to a decorative sheet designed to give a three-dimensional appearance to a pattern printed on a sheet surface.
2. Description of the Related Art
A typical decorative sheet has a pattern such as a picture, letter or mark merely printed on a base sheet and is therefore lacking in a three-dimensional appearance or depth of the pattern. Various attempts have been made to give an enhanced three-dimensional appearance to a pattern. As this kind of decorative sheet, for example, a decorative sheet disclosed in Japanese Patent Laid-Open Publication No. HEI-6-182937 is known.
The known decorative sheet has a structure in which a printed pattern is formed on a transparent resin layer including squamiform particles. Thus, in the decorative sheet, the addition of the transparent squamiform particles to the transparent resin results in different looks of a distance from the surface of the transparent resin layer to the printed pattern according to position, thereby supplying perspective and a three-dimensional appearance to the pattern.
The aforementioned conventional decorative sheet supplies perspective with a large number of squamiform particles in the transparent resin layer with a limited thickness and therefore has a limit in largely increasing a three-dimensional appearance. In order to provide an improved three-dimensional appearance, it is required to increase the thickness of the transparent resin layer. However, the thicker the transparent resin layer is, the thicker the decorative sheet as a whole is, resulting in an inferior appearance. Further, when it is a flexible decorative sheet, increase in thickness of the transparent resin layer reduces flexibility of the sheet and thus is an inexpedient measure.
The present invention has been attained in view of the above problems. It is accordingly an object of providing a decorative sheet in which a three-dimensional appearance of a pattern is further improved without increasing the thickness of the decorative sheet.
According to an aspect of the present invention, there is provided a decorative sheet comprising a reflective layer for reflecting light, a transparent layer formed on the reflective layer, a light shielding layer formed on the transparent layer, a pattern layer containing a letter, figure, mark or the like interposed between the light shielding layer and the reflective layer, and a plurality of through holes provided in the light shielding layer for passing an incident light beam toward the reflective layer or an emission light beam which leads out a pattern image reflected in the reflective layer.
Thus, in the present invention, a pattern of the pattern layer interposed between the reflective layer and the light shielding layer is reflected in the reflective layer, and the reflected image of the pattern can be seen through the through holes from the light shielding layer side. Since what is seen is an image of a pattern reflected in the reflective layer, a path in which an incident light beam strikes the pattern layer, and via the reflective layer, reaches the through hole as an emission light beam is longer. The longer length of the path makes it possible to see the pattern as an image with an enhanced three-dimensional appearance, thereby eliminating the need for increasing the thickness of the decorative sheet.
Desirably, the pattern layer is provided on the rear surface of the light shielding layer.
It is preferred that each part of the pattern layer interposed between the reflective layer and the light shielding layer be interposed in an arbitrary different position because the length of an optical path in which an incident light beam strikes each part of the pattern, and via the reflective layer, reaches the through hole as an emission light beam is different from each other, resulting in a further enhanced three-dimensional appearance.
In the present invention, projections protruding toward the transparent layer and constituting a pattern can be integrally formed on the rear surface of the light shielding layer, and further projections protruding toward the transparent layer can be integrally formed on the internal surface of the reflective layer.
A protective layer made of light transmissive resin or glass is formed on the light shielding layer for protecting the decorative surface of the decorative sheet from damage. In this case, a refractive index of the protective layer is substantially equal to that of the transparent layer.
If a supplementary transparent layer having a light refractive index different from that of the transparent layer is formed on the light shielding layer, refraction of an emission light beam is changed. This makes it possible to set the opening width of the through holes arbitrary.
If a lining layer for reflecting light is interposed between the light shielding layer and the pattern layer, the contrast between the light shielding layer and the pattern layer is preferably clarified.